Transfer roller assembly

ABSTRACT

A transfer roller assembly including a transfer roller for an electrostatographic machine. The transfer roller assembly is rotated about a support shaft in response to spring tension to place the transfer roller in pressure contact with the photoconductive surface during the image transfer mode therefore. The transfer roller assembly is rotated in the opposite direction by removal of such spring tension for diverse reasons, for example to facilitate replacement of the photoconduct member.

United States Patent [191 Hoffman et a].

[451 Oct. 22, 1974 1 1 TRANSFER ROLLER ASSEMBLY [73] Assignee: Xerox Corporation, Stamford,

Conn.

[22] Filed: Dec. 30, 1971 [21] Appl. No.: 214,289

[52 us. Cl. 118/637, 118/249.

[51] lint. Cl G03g 13/00 [58] Field of Search 118/247, 249, 262, 637; 96/1.4

[56] References Cited UNITED STATES PATENTS 206,276 7/1878 Spencer 118/249 1,184,497 5/1916 Vuono 118/249 1,407,612 2/1922 White 118/262 2,051,222 8/1936 Odell 91/51 2,533,574 12/1950 Gerlach 91/48 2,666,412 l/l954 Ford 118/267 2,915,038 12/195 Wallenherg 1111/24) 1,093,325 6/1963 'l'rumhull l IH/o II 3.105.777 /1963 Bickmorc cl ul. Nil/0, 7 3,526,457 9/1970 Dimond ct al 96/14 X 3,592,642 7/1971 Kaupp 96/1.4 3,691,993 9/1972 Krause 118/637 Primary Examiner-Robert R. Mackey Assistant Examiner-Leo Millstein 5 7 ABSTRACT A transfer roller assembly including a transfer roller for an electrostatographic machine. The transfer roller assembly is rotated about a support shaft in response to spring tension to place the transfer roller in pressure contact with the photoconductive surface during the image transfer mode therefore, The transfer roller assembly is rotated in the opposite direction by removal of such spring tension for diverse reasons, for example to facilitate replacement of the photoconduct member.

2 Claims, 7 Drawing Figures v PATENTE,U

shin zor a TRANSFER ROLLER ASSEMBLY BACKGROUND OF THE INVENTION This invention relates to electrostatography, and more particularly to a novel transfer roller assembly for an electrostatographic apparatus.

In the practice of xerography as described in US. Pat. No. 2,297,691 to Chester F. Carlson, a xerographic surface comprising a layer of photoconductive insulating material affixed to a conductive backing is used to support electrostatic images. In the usual method of carrying out the process, the xerographic plate is electrostatically charged uniformly over its surface and then exposed to a light pattern of the image being reproduced to thereby discharge the charge in the areas where light strikes the layer. The undischarged areas of the layer thus form an electrostatic charge pattern in conformity with the configuration of the original light pattern.

by contacting it with a finely divided electrostatically attractable materiaLsuch as a resinous powder. The powder is held in the image areas by the electrostatic fields on the layer. Where the field is greatest, the greatest amount of material is deposited; and where the field is least, little or no material is deposited. Thus,'a powder image is produced in conformity with the light image of the copy being reproduced. The powder is subsequently transferred to a sheet of paper or other surface and suitably affixed to thereby form a perinanent print.

The toner may be fixed by passing the sheet of paper or other surface including the transferred image between a heated roller and a second roller in pressure contact therewith whereby the toner becomes fused to the sheet of paper.

The image is generally transferred to an image receiving member by passing such a member between the photoconductive surface including the developed image and a roller in contact therewith/In, order to transfer effectively any such image there is need for uniform contact along the nip of the photoconductive surface and the transfer roller.

OBJECTS OF THE INVENTION achieved.

SUMMARY OF THE INVENTION These and other objects of the invention are obtained by providing a transfer roller assembly rotatably supported within the housing of an electrostatographic machine in juxtaposition to a photoconductive surface therefor. The transfer roller assembly is provided with bracket means which engage spring loaded lever ele-' ments rotatably mounted on a locking shaft mounted The latent electrostatic image may then be developed 2 for rotation in the housing of the machine. The locking shaft is provided with a handle for moving the shaft to an image transfer mode with the concomittant nominal rotation of the transfer roller assembly thereby bring the transfer roller into uniform contact with the photoconductive surface.

DESCRIPTION OF THE DRAWINGS A better understanding of the present invention as well as other objects and further features thereof will become apparent upon consideration of the following detailed disclosure thereof, especially when taken with the accompanying drawings, wherein like numerals designate like parts throughout.

FIG. 1 is a schematic sectional view of an electrostatic reproduction machine embodying the principles of the invention.

FIG. 2 is an end view of the transfer roller assembly.

FIG. 3 is an isometric view (greatly simplified) of the transfer roller assembly.

FIG. 4 is a partialrear view in section of the transfer roller assembly taken along the lines 4-4 of FIG. 2;

FIGS is a rear view of the locking shaft assembly;

FIG. 6 is a side elevation view of amounting frame for the transfer roller assembly; and

FIG. 7 is a side view of the transfer roller assembly illustrating the movement thereof when disposed in juxtaposition to a photoconductive 'belt of an electrostatographic machine.

For a general understanding of the illustrated copier/reproduction machine in which the invention may be incorporated, reference is had to FIG. 1 in which the various system components for the machine are schematically illustrated.

A document D to be copied is placed upon a transparent support platen P fixedly arranged in an illumination assembly, generally indicated by the reference numeral 10, positioned at the left end of the machine.

Light rays from an illumination system are flashed upon the document to produce image rays corresponding to the'informational areas. The image rays are projected by means of an optical system onto the photosensitive surface of a xerographic plate in the form of a flexible photoconductive belt 12 arranged on abelt assembly, generally indicated by the reference numeral 14.

The belt 12 comprises a photoconductive layer of selenium which is the light receiving surface and imaging medium for the apparatus, on a conductive backing. The surface of the photoconductive belt is made photosensitive by a previous step of uniformly charging the same by-means of a corona generating device or corotron 13. I

The belt is journaled for continuous movement upon three rollers 20, 21 and 22 positioned with their axes in parallel. The photoconductive belt'assembly 14 is slidably mounted upon two support shafts 23 and 24 with the roller 22 rotatably supported on the shaft 23 i which is secured to the frame of the apparatus and is rotatably driven by a suitable motor and drive assembly (not shown) in the direction of the arrow at a constant rate. During exposure of the belt 12, the portion exposed is that portion of the belt running between rollers 20 and 21. During such movement of the belt 12, the reflected light image of such original document positioned on the platen is flashed on the surface of the belt to produce an electrostatic latent image thereon at exposure station A.

As the belt surface continues its movement, the electrostatic image passes through a developing station B in which there is positioned a developer assembly generally indicated by the reference numeral 15, and which provides development of the electrostatic image by means of multiple brushes 16 as the same moves through the development zone.

The developed electrostatic image is transported by the belt to a transfer station C wherein the present invention may be positioned and whereat a sheet of copy paper is moved between a transfer roller and the belt at a speed in synchronism with the moving belt in order to accomplish transfer of the developed image solely by' an electrical bias on the transfer roller. There is provided at this station a sheet transport mechanism generally indicated at 17 adapted to transport sheets of paper from a paper handling mechanism generally indicated by the reference numeral 18 to the developed image on the belt at the station C.

After the sheet is stripped from the belt 12, it is conveyed into a fuser assembly, generally indicated by the reference numeral 19, wherein the developed and transferred xerographic powder image on the sheet material is permanently affixed thereto. After fusing, the finished copy is discharged from the apparatus at a suitable point for collection externally of the apparatus.

Further details regarding the structure of the belt assembly l4 and its relationship with the machine and support therefor may be found in the copending Application Ser. No. 102,312 assigned to the same assignee.

Referring now to FIGS. 2, 3 and 4, there is illustrated a transfer roller assembly, generally indicated as 30, comprised of a transfer roller 32 mounted for rotation about a shaft 34 in hub assemblies 36. A gear 38 is affixed to an end of the shaft 34 extending through the hub assembly 36 and engages an endless belt 40 to rotate the transfer roller 32 through a suitable drive assembly, generally indicated as 42. A support shaft 44 is mounted for rotation in hub assemblies 36 above the transfer roller 32 in coaxial alignment therewith and extends outwardly beyond the hub assemblies 36. A gear 46 is affixed to the shaft 44 and similarly engages the endless belt 40. Bearings 48 are positioned on the ends of the shaft 44 and are positioned in frame support assemblies, generally indicated as 50 and 52 (see FIGS. and 6).

The frame suport assemblies 50 and 52 are comprised of a frame section 54 having a cylindrically shaped machined surfaces 56 for receiving the bearings 48 of the support shaft 44. An upwardly extending tab section 58 is formed on the frame section to receive a clamp 60 pivotally mounted to the tab section 58, such as by a pin 62. The clamp 60 is held in locking relationship to the frame section 54 by a screw 64. The frame section 54 is provided with a shaft receiving orifice 66 and mounting holes 68 for affixing the frame assembly handle 74 is affixed to the shaft 72 at an intermediate position thereof for rotation of the shaft to a locking attitude, as more fully hereinafter discussed. Positioned on either side of the shaft 72, there are affixed spring retaining assemblies 76 in which is positioned one end I of springs 78. The other end of the springs 78 are af- 52 to the main body (not shown) of the electrostatofixed to lever elements 80 mounted for rotation about the shaft 72 and having an outwardly extending pin sections 82. Each pin section 82 engages grooved sections I 84 formed on an outer surface of the hub assemblies 36 (See FIG. 2). The handle 74 is positioned within a receiving plate 86 having a U-shaped opening '90 mounted to a hub assembly,generally indicated as 98, such as by screws 94.

Referring to FIG. 7, to place the transfer roller 32 in pressure contact with the photoconductive surface, generally indicated as 96, the handle 74 is moved clockwise from the position A, illustrated by the solid lines to position B, illustrated by the dotted lines and locked against counterclockwise rotation in the opening 90 of the receiving plate 86 thereby rotating assembly, generally the shaft 72. Such rotation of the shaft 72 causes the lever elements to rotate clockwise about the shaft 72 forcing the pin section 82 thereof to press against one side of the cooperating grooves 84 on the hub assemblies thereby forcing under spring tension the transfer roller assembly 30 against the photoconductive surface 96. This relationship of pressure contact of the transfer roller 32 with the photoconductive member 96, facilitates image transfer and permits the transfer roller 32 and photoconductive member 96 to function as part of the transport system for image receiving members. Shifting of the handle from the locking position B to the position A releases the forces that the pins 82 have upon the side of the grooves 84 causing counterclockwise movement of the transfer roller assembly 30 away from the photoconductive surface thereby facilitaing the correction of paper jams and to permit removal of the photoconductive members from the machine.

Other modifications of the present invention will occur to those skilled in the art upon a reading of the present disclosure which modifications are intended to be included within the scope of this invention.

What is claimed is:

1. An improved electrostatographic machine having a photoconductive member, the improvement comprismg:

a transfer roller assembly mounted for rotation within said machine, said assembly including end members each having groove means formed therein, a transfer roller rotatably mounted to said end members, a mounting shaft parallel to said transfer roller and rotatably mounted to said end members, bearing means for mounting said mounting shaft within said machine, said assembly being adapted to rotate about the axis of said mounting shaft, said transfer roller being disposed adjacent said photoconductive member,

means for placing said transfer roller in pressure contact with said photoconductive surface, said placing means including a locking shaft rotatably mounted parallel to said transfer roller, a handle connected to said locking shaft for rotating the same, an arm mounted on each side of said handle, each of said arms being mounted to rotate with respect to said locking shaft and having means for enhaving a generally U-shaped opening, and wherein said handle is positioned within said opening, and wherein one leg of said opening is adapted to engage said handle in locking attitude for maintaining the pressure contact between said photoconductive member and said transfer roller. 

1. An improved electrostatographic machine having a photoconductive member, the improvement comprising: a transfer roller assembly mounted for rotation within said machine, said assembly including end members each having groove means formed therein, a transfer roller rotatably mounted to said end members, a mounting shaft parallel to said transfer roller and rotatably mounted to said end members, bearing means for mounting said mounting shaft within said machine, said assembly being adapted to rotate about the axis of said mounting shaft, said transfer roller being disposed adjacent said photoconductive member, means for placing said transfer roller in pressure contact with said photoconductive surface, said placing means including a locking shaft rotatably mounted parallel to said transfer roller, a handle connected to said locking shaft for rotating the same, an arm mounted on each side of said handle, each of said arms being mounted to rotate with respect to said locking shaft and having means for engaging one of said groove means, and a spring mounted on each side of said handle, each of said springs being disposed around said locking shaft and having one end fixed so as to rotate with said locking shaft when the latter rotates while the other end is affixed to one of said arms.
 2. An improved electrostatographic machine according to claim 1, and further including a locking plate having a generally U-shaped opening, and wherein said handle is positioned within said opening, and wherein one leg of said opening is adapted to engage said handle in locking attitude for maintaining the pressure contact between said photoconductive member and said transfer roller. 